1. Field of the Invention
The present invention relates to a pulse width modulation (PWM) controller for a power converter, and more specifically relates to a PWM controller for switching mode power converters.
2. Description of Related Art
Various power converters have been widely used to provide regulated voltage and current. For the sake of safety reasons, an off-line power converter must provide galvanic isolation between its primary side and secondary side. In case that a control circuit is equipped at the primary side of the power converter, an opto-coupler and a secondary-side regulator are needed to regulate an output voltage and an output current of the power converter. The object of the present invention is to provide a PWM controller for controlling the output voltage and the output current of the power converter at the primary side without the need of the opto-coupler and secondary-side regulator. Therefore, the size and the cost of the power converter can be reduced.